1. Field of the Invention
The invention relates to semiconductor devices and more specifically to a disc-shaped thyristor having a cathode and gate electrode on one major surface and an anode electrode on a second major surface with the thyristor encapsulated by fusing glass directly to the body of semiconductor material.
2. Description of the Prior Art
Prior art semiconductor devices using glass fused directly to the semiconductor portion of the device as a sole means for protecting the PN junctions from the environment have been limited to relatively low current diodes. An example of such a diode is type UT4005 manufactured and sold by the Unitrode Corporation. It is also known in the prior art to encapsulate semiconductor devices in thermosetting resinous insulating material. Examples of such hermetically sealed devices using resinous material are disclosed in U.S. Pat. Nos. 3,475,662, 3,476,978, and 3,476,988 as well as 3,486,084. Thin glass protective layers are also available in the prior art to passivate semiconductor devices. These thin passivation layers was typically applied to the body of semiconductor material as a slurry and the device and the powered glass were heated to fuse the glass to form a passivating glass layer. Glass layers formed using this technique where limited in thickness to the order of 20 or 30 microns. These thin layers are not sufficient to provide complete environmental protection for the PN junctions within the semiconductor material.